package com.hmdp.utils;

import cn.hutool.core.lang.func.Func;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

@Slf4j
@Component
public class CacheClient {

    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit){
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));

        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R,ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time, TimeUnit unit){
        String key= keyPrefix +id;
        // 1.从redis查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if(StrUtil.isNotBlank(json)){
            // 3.存在，直接返回
            return JSONUtil.toBean(json,type);
        }
        // 判断命中的是否是空值
        if(json!=null){
            return null;
        }

        // 4.不存在，根据id查询数据库
        R r= dbFallback.apply(id);
        // 5.不存在，返回错误
        if(r==null){
            stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        // 6.存在，写入redis
        this.set(key,r,time,unit);

        return r;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time, TimeUnit unit){
        String key= keyPrefix +id;
        String json = stringRedisTemplate.opsForValue().get(key);

        if(StrUtil.isBlank(json)){
            return null;
        }

        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();

        if(expireTime.isAfter(LocalDateTime.now())){
            return r;
        }

        String lockKey=RedisConstants.LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        if(isLock){
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    R r1 = dbFallback.apply(id);
                    this.setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unlock(lockKey);
                }
            });
        }
        return r;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }



}
